Color coding of pulp insulated conductors

ABSTRACT

A method and apparatus for the intermittent marking or color coding of an absorbent sheath on a continuous wire strand, obtained by forming pulp material as a ribbon parallel to the wire and wrapping the pulp ribbon laterally about the wire, in which lateral stripes of dye are applied at spaced intervals to that surface of the pulp ribbon opposite the wire after the ribbon is formed and before it is wrapped around the wire. The dye stripes are applied to the pulp ribbon, while wet, by a marking roller located between a pulp vat and a polisher, and the stripes extend laterally the width of the ribbon.

United States Patent Braim [151 3,663,359 [451 May 16, 1972 [54] COLOR CODING OF PULP INSULATED CONDUCTORS [73] Assignee: Northern Electric Company Limited, Montreal, Quebec, Canada [22] Filed: May 1, 1970 [21] Appl.No.: 33,771

[52] US. Cl ..162/105, 101/219, 118/221, 118/262, 156/53, 162/106, 162/134, 162/138,

[51] Int. Cl. ..DZlh 3/82 [58] Field ofSearch ..162/l05,106, 118, 119,120, 162/122, 134, 138, 267, 268,283,287; 101/219;

[56] References Cited UNITED STATES PATENTS 3,365,357 l/l968 Korgel et a1. ..162/106 2,186,555 1/1940 Phillips ..174/112 UX 3,597,311 8/1971 Jachimowicz et a1 ..162/138 X FOREIGN PATENTS O R APPLICATIONS 591,647 8/ 1947 Great Britain ..174/1 12 Primary Examiner-S. Leon Bashore Assistant Examiner-Arthur L. Corbin Attorney-Westell and Hanley [57] ABSTRACT A method and apparatus for the intermittent marking or color coding of an absorbent sheath on a continuous wire strand, obtained by forming pulp material as a ribbon parallel to the wire and wrapping the pulp ribbon laterally about the wire, in which lateral stripes of dye are applied at spaced intervals to that surface of the pulp ribbon opposite the wire after the ribbon is formed and before it is wrapped around the wire. The dye stripes are applied to the pulp ribbon, while wet, by a marking roller located between a pulp vat and a polisher, and the stripes extend laterally the width of the ribbon.

6 Claims, 4 Drawing Figures Patented May 16, 1972 FIG] INVENTOR. DAVID H. BRAIM COLOR CODING OF PULP INSULATED CONDUCTORS The present invention relates to the colorcoding of wire strands and more particularly to the intermittent marking of an absorbent sheath on a continuous strand such as a fibrous insulated wire or cable.

Wires insulated with an absorbent sheath are commonly used in multi-strand cables and the individual strands in the cable are identified by Color coding, i.e. by coloring the strands with different dyes or inks. A common type of absorbent sheath used to insulate the wires is fibrous pulp such as the pulp of manilla, wood, rag, cotton, jute, hemp or asbestos. Pulp may be colored by adding dye to the vat of pulp being used to coat the wire or the dye may be applied by passing the insulated strands through a separate dye vat or by spraying. However, it is' not possible to use this procedure to obtain intermittent or longitudinally spaced dye markings on a strand. Furthermore, while it is preferable to apply the dye to an ab sorbent sheath when the sheath is wet to limit the penetration of the dye into the sheath material, the wet sheath material is structurally very weak and is easily damaged, making it difficult to apply dye to form accurate circumferential or annular rings on the sheath.

It is an object of the present invention to provide an improved method and apparatus for applying spaced circumferential markings on the absorbent sheaths of fiber insulated continuous wire strands.

An example embodiment of the invention is shown in the accompanying drawings in which:

FIG. 1 is a schematic flow diagram showing the steps of forming pulp insulation on a wire strand, including the step of marking the insulation according to the present invention;

FIG. 2 is a view in perspective of the marking roller and the guide roller shown in FIG. 1;

FIG. 3 is a fragmentary view in perspective of the pulp ribbon insulation and contiguous wire strand after passing the marking roller; and

FIG. 4 is a view similar to FIG. 3, with the pulp ribbon polished on the wire strand to form the color coded insulation.

In the schematic flow diagram of FIG. 1, a continuous strand of bare metal wire as shown in cross-section A is unwound from a supply spool 11 into a pulp vat 12 where it passes around a cylinder mould l3 partiallysubmerged in pulp liquid 14. Wire 10 emerges from vat 12 parallel to, and embedded in, one side of a tape or ribbon 15.0f pulp insulation as shown in cross section B. Wire 10 and pulp ribbon 15 next pass between a guide roller 16 and a printingor marking roller 17 which is one member of a marking unit 18, and then the wire and ribbon pass on through a polisher 19 between shoes 20, axially rotated by a motor 21, which wraps the lateral portions of the pulp ribbon around the wire to form an annular insulating sheath 22, thus producing a pulp insulated wire strand 23 as shown in cross-section C. Strand 23 passes through a drying oven 24 where the moisture carried by the pulp of sheath 22 and the dye on the sheath from marking roller 17 is evaporated to produce a dry strand which is wound on a takeup spool 25 for storage.

As shown in FIG. 1 and 2 of the drawings, marking unit 18 comprises a printing or marking roller as 17 having a patterned rubber surface 26, a transfer roller 27 in running contact with marking roller 17, a stain liquid pick-up or supply roller 28 in running contact with transfer roller 27 and partly immersed in a stain tray 29, and a squeeze roller 39 in running contact with supply roller 28. Rollers l6, 17, 27, 28, and 30 are journalled for rotation about longitudinal shafts 31 (which are all parallel one to another) and a drive mechanism may be coupled with one or more of shafts 31 although rotation of the rollers by surface contact of wire 10 and pulp ribbon 15 is preferred to reduce the possibility of damage to the pulp ribbon. In the illustrated embodiment, the pattern of rubber surface 26 on marking roller 17 consists of circumferentially spaced raised ribs having flat faces.

In the operation of the example embodiment, wire 10 is drawn in a continuous strand from reel 11, passing around cylinder mould 13 and through pulp liquid 14 to emerge from vat l2 embedded in one side of pulp ribbon 15 as described above and shown in cross-section B. Pulp ribbon 15, with wire 10 embedded in one side of the ribbon, next passes over guide roller 16 and under marking roller 17 with that side of the pulp ribbon carrying wire 10 in contact with the guide roller and the opposite surface of the ribbon being contacted by patterned rubber surface 26 of marking roller 17, as shown in FIG. 2 of the drawings. Rollers l6 and 17 rotate at the same peripheral velocity to avoid any shear stresses on ribbon l5, and the compressive stress imparted by these rollers to the ribbon is also adjusted to prevent structural damage to the ribbon. As marking roller 17 rotates in unison with the rollers of marking unit 18, dye in tray 29 is picked up by roller 28. Excess dye is squeezed off roller 28 by roller 30 and the remaining dye on roller 28 is transferred onto roller 27. During the rotation of roller 17, raised ribs 32 on surface 26 of the roller come into contact with transfer roller 27 and with pulp ribbon 15 to transfer the dye onto the pulp ribbon in the form of spaced lateral stripes or markings 33 each extending the width of the ribbon. Marked ribbon 15 with wire 10 embedded in one side of the ribbon is then passed through polisher 19 and emerges from the polisher, as shown in FIG. 4, with ribbon l5 wrapped around wire 10 to form an annular sheath 22 having marking 33 appearing circumferentially and at spaced intervals along it. Sheath 22 is then dried by passing strand 23 through oven 24, after which the insulated and coded strand is stored on take-up reel 25.

It will be seen from the operation of the example embodiment that a complete and accurate circumferential marking of a pulp insulated strand is produced by converting plane markings into annular rings. Furthermore, as the marking is applied when the pulp insulation is wet, the dye does not penetrate into the insulation to weaken it structurally.

It will be appreciated that the configuration of ridges 32 on surface 26 of marking roller 17 determines the pattern of markings 33 on pulp ribbon 15. Also, while only the production of only a single pulp insulated strand 23 is shown in the example embodiment for simplification, it would be usual to use the invention in the simultaneous production of a plurality of the strands for forming a band of parallel pulp ribbons l5 (and wires 10) emerging from pulp vat 12.

I claim:

1. In a method for producing a wire strand insulated with a sheath of absorbent material marked longitudinally at spaced intervals, in which the absorbent material is formed as a wet ribbon parallel to the wire and subsequently wrapped laterally around the wire to form the sheath, the step of applying stripes of dye at spaced intervals along that surface of the wet ribbon opposite the wire with each stripe extending laterally the width of the ribbon.

2. A method as claimed in claim 1 in which the ribbon is passed between a pair of parallel rollers and in contact with each roller, the surface of one roller having circumferentially spaced longitudinal marking ribs carrying liquid dye on the surface thereof for transfer to the ribbon.

3. A method as claimed in claim 1 in which a plurality of ribbons travelling parallel one to another in a band are marked simultaneously.

4. In an apparatus for producing a wire strand insulated with a sheath of absorbent material marked longitudinally at spaced intervals, in which the wire is passed through a pulp vat and absorbent material is formed as a wet ribbon parallel to the wire, the wet ribbon being subsequently wrapped laterally around the wire by a polisher to form the sheath,

marking means located adjacent the line of travel of the ribbon between the vat and the polisher to apply stripes of dye at spaced intervals along that surface of the ribbon tape opposite the wire with each stripe extending laterally the width of the ribbon.

5. Apparatus as claimed in claim 4 in which the marking means comprises a guide roller and a marking roller with the ribbon passing therebetween, the surface of the marking roller having circumferentially, spaced longitudinal ribs, and means to apply liquid dye to the ribs of the marking roller for transfer to the ribbon.

6. Apparatus as claimed in claim 5 in which the means for applying liquid dye to the ribs of the marking roller comprise a 

2. A method as claimed in claim 1 in which the ribbon is passed between a pair of parallel rollers and in contact with each roller, the surface of one roller having circumferentially spaced longitudinal marking ribs carrying liquid dye on the surface thereof for transfer to the ribbon.
 3. A method as claimed in claim 1 in which a plurality of ribbons travelling parallel one to another in a band are marked simultaneously.
 4. In an apparatus for producing a wire strand insulated with a sheath of absorbent material marked longitudinally at spaced intervals, in which the wire is passed through a pulp vat and absorbent material is formed as a wet ribbon parallel to the wire, the wet ribbon being subsequently wrapped laterally around the wire by a polisher to form the sheath, marking means located adjacent the line of travel of the ribbon between the vat and the polisher to apply stripes of dye at spaced intervals along that surface of the ribbon tape opposite the wire with each stripe extending laterally the width of the ribbon.
 5. Apparatus as claimed in claim 4 in which the marking means comprises a guide roller and a marking roller with the ribbon passing therebetween, the surface of the marking roller having circumferentially spaced longitudinal ribs, and means to apply liquid dye to the ribs of the marking roller for transfer to the ribbon.
 6. Apparatus as claimed in claim 5 in which the means for applying liquid dye to the ribs of the marking roller comprise a supply roller partially immersed in a pool of liquid dye, a squeeze roller in running contact with the supply roller, and a transfer roller in running contact with both the supply roller and the marking roller. 